The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to perform etching, deposition, and/or other treatment of substrates such as semiconductor wafers. Example processes that may be performed on a substrate include, but are not limited to, etching, deposition and cleaning processes. During processing, a substrate is arranged on a substrate support, such as a pedestal, an electrostatic chuck (ESC), etc. in a processing chamber of the substrate processing system. A gas delivery system supplies a gas mixture into the processing chamber to treat the substrate. Plasma may be struck to enhance chemical reactions within the processing chamber. An RF bias may also supplied to the substrate support to control ion energy.
To improve quality and reduce defects, one or more metrology systems may be used to verify operation of the processing chamber. For example, a flow metrology system may be used to verify flow rates of a gas delivery system supplying the gas mixture. When multiple substrate processing chambers are arranged in a substrate processing tool, gas lines are used to connect the gas delivery systems of the processing chambers to a multiplexed flow metrology system.
The flow metrology system may include an orifice-based, steady-state flow measurement device. Gas delivery systems are typically required to calibrate and supply flow rates from 10-3000 sccm. Gas flowing into the gas lines at low flow rates takes a long time to reach the flow metrology device and build up sufficient pressure for measurement, which adversely impacts measurement times during tool-startup. In other words, calibrating flow rates from 10 to a few hundred sccm take a long time. More recently, process recipes also require calibration and supply of flow rates from 0.1-10 sccm. As can be appreciated, unacceptable time delays may occur during calibration or chamber matching of the lower flow rates from 0.1 to 10 sccm using the orifice-based method.